Field of the Invention
The present disclosure relates to a material for an electronic device, and more particularly to a CBS (CaO—B2O3—SiO2)-based low-temperature co-fired ceramic (LTCC) material, and a preparation method thereof.
Related Arts
With the rapid development of modern information technology, higher requirements are imposed on the electronic products in terms of miniaturization, lightweight, multiple functions, reliability, low cost and others. Low Temperature Co-fired Ceramic (LTCC) technology is an advanced passive integrated and hybrid circuit packaging technology, which has become a preferred way to integrate electronic components in the future. In this context, the low-temperature co-firing of the main dielectric materials has also become an important development trend.
In view of the use, the LTCC material needs to have the properties of low dielectric constant, low dielectric loss, high self-resonant frequency, high resistivity, low sintering temperature (≤900° C.), capability of co-firing with an electrode material such as silver and copper, high mechanical performance, and so on. The CaO—B2O3—SiO2-based LTCC material having wollastonite (β-CaSiO3, dielectric constant ∈r=5, dielectric loss tan δ=0.01-0.03%) as a main crystal phase receives great attention due to the excellent dielectric and thermal properties, and the capability of co-sintering with the noble metals Ag and Au at a low temperature (<950° C.). At present, the CBS-based LTCC material is mainly prepared through the following processes.
(1) Solid-phase synthesis—As a traditional electronic ceramic technology, the solid-phase synthesis has the advantages of simple process, no occurrence of composition deviation, high stability, high feasibility of mass production, and low cost, but has high sintering temperature in the event of doping no sintering aid. In “Study on CaO—B2O3—SiO2 LTCC Materials Prepared by Solid State by Yang Shilin et al from University of Electronic Science and Technology of China, the optimum sintering temperature is up to 950° C. by adjusting the main component CBS. The CBS-based LTCC material prepared through solid-phase synthesis by He Ming et al from University of Electronic Science and Technology of China by adding the nucleating agents TiO2 and ZrO2 also has a sintering temperature of up to 950° C. The too high sintering temperature causes high energy consumption, which go against the co-sintering with Ag at a low temperature. Therefore, this limits the application of CBS in LTCC to a certain extent.
(2) High-temperature sintering—High-temperature sintering is a process in which the initial raw materials are mixed evenly, melted into a liquid at a high temperature, and then quenched in water to form glass; and the glass is ground into a fine material, thermally treated at 850° C. (crystallization and nucleation) to obtain “glass-ceramic”. However, B2O3 is volatile in the melting process, causing the composition to deviate from the formula designed. This harms the performance. Meanwhile, the instability existing in the glass preparation may easily lead to the instability between batches during the mass production of the powder. Therefore, the stability and reliability are difficult to control.
(3) Sol-gel process—Sol-gel process is a method in which a lipid containing the glass component is hydrolyzed into a gel, which is dried and thermally treated to obtain a glass-ceramic material. However, there are problems such as high preparation cost, complicated heat treatment and difficult mass production.